But experts also say they can be avoided if parents heed a handful of simple lessons.

The Kansas girl is at least the 18th child to have died unattended in hot vehicles so far this year — and each death was "100 percent avoidable," Transportation Secretary Anthony Foxx said at a "Where's Baby? Look Before You Lock" event this week in Washington.

That's not out of the ordinary. Thirty to 50 children die in hot vehicles every year, with the numbers spiking in June, July and August, according to statistics compiled by the activist group KidsAndCars.org.

More telling are the stories that don't get as much attention: the incidents when children survive, thanks to intervention by authorities or passing heroes, as when Taylor Manning grabbed a tire iron and smashed the window of a car in which a little girl was trapped in Leander, Texas.

No one formally keeps track of non-fatal cases, but they're frighteningly common. Through Friday, NBC News found that authorities or passersby had to rescue at least 164 other kids ages 16 and under who were left in at least 87 hot vehicles across the U.S.

The cases are all different, but a few consistent strains run through them, offering lessons for parents and guardians.

Cars Become Ovens Very Quickly

It takes almost no time at all for a closed car to turn into a blast furnace, as happened July 3 when a Maryland man left his 2-year-old daughter in his car, its windows closed, as he was shopping in Long Island, New York. One of the responding officers, who estimated the car's internal temperature at 120 degrees, said the girl was "beet red [with] drips of sweat coming off her face" after less than half an hour alone in the car.

It was an alert passerby who spotted the toddler and called police. She was treated for heat exhaustion, and her father has pleaded not guilty to child endangerment and reckless endangerment.

Similarly, employees of a grocery store in Hazlehurst, Georgia, spotted three children — ages 16, 2 and 3 months — in a closed car in the parking lot July 8. Investigators estimated the car's internal temperature at 118 degrees, again after less than 30 minutes. Their parents were charged with misdemeanor reckless conduct.

It Can Happen to Anyone

"It's mind-boggling to me that someone can leave — better yet, forget — about a child inside of a vehicle," Slidell, Louisiana, Police Chief Randy Smith said after a woman left her 5-week-old infant in a locked car while she went shopping July 1. The newborn made a full recovery, and the mom was charged with second-degree cruelty to juveniles.

But it's sometimes not that simple. Even the most conscientious of guardians can slip up, as happened to a veteran foster mother in Apopka, Florida. She was charged with child neglect after she left one of her wards, a 15-month-old boy, in her hot SUV at the grocery store for about 20 minutes on July 10. The boy had pinkeye, and she didn't want to expose him to the public.

The woman — who was so well thought of that she was a mentor for other foster parents — was deeply remorseful and voluntarily relinquished her foster care license before authorities could move to revoke it. She was charged with felony child neglect. The child recovered.

Time Can Get Away From You

Authorities say even good parents sometimes simply lose track of how long they've been away while their child is in the car. A Florida woman said she had no idea she'd been inside a Costco store in Jacksonville for at least 45 minutes on July 6 because her watch was broken. All the time, a 5-year-old girl was locked inside her car in the parking lot on an 87-degree day.

Police were called after the girl — whose precise relationship to the woman was redacted in a police incident report — put up a handmade card complaining that she'd gotten very hot. The girl was OK, and the woman was charged with child neglect.

Be Vigilant Year-Round

Cases like these drive home the need for parents and guardians to always be aware of where their children are.

"To me, you'd just naturally want to know where they are every minute," Edwin Fletcher, a grandfather of four, told NBC station WLTV of Jacksonville after the arrest at the Florida Costco.

"Young kids like that, you have to keep your eye on them every second," Fletcher said. "If they're not with you every second within eyesight, it shouldn't be too many seconds gone before you want to know: 'Where is the kid?'"

After an 18-month-old boy was left sleeping inside the family car in the driveway of a Yulee, Florida, home on July 8, Jessica Winberry, community health educator with Wolfson Children's Hospital in Jacksonville, said no one should be surprised.

"About 52 percent are being left by accident, meaning they're forgotten," Winberry told WLTV. "A parent thinks that they've gotten the child out of the car."

While most incidents involving children being treated for heat exhaustion after being left in cars happen in the summer, "don't be lulled into the idea that it can't happen in cooler months," Winberry said. "We do see our first deaths happening in 70-degree weather."